Caused when all or any part of the song "Friday" by Rebecca Black is stuck in one's head. Symptoms include tendency to complain and urge to sing the song. Can be spread by simply mentioning the song to someone. Can only be prevented by heavy listening to an individual's favorite artist.

I can't get the song Friday out of my head." "Crap, now it's stuck in my head, the black plague 2.0 is spreading